Permittivity and density of the systems (monoglyme, diglyme, triglyme, or tetraglyme + n-heptane) at several temperatures

Abstract

Relative permittivity and density on mixing at atmospheric pressure and temperatures from (288.15 to 308.15) K and atmospheric pressure have been measured over the entire composition range of mixing for {CH 3O(CH 2CH 2O) m CH 3 with m = 1, 2, 3, 4 (also called monoglyme, diglyme, triglyme, or tetraglyme) + n-heptane}. The permittivity values were fitted as a function of the volume fraction and temperature to a logarithmic equation. The excess permittivity is calculated considering a definition that has been recently established in terms of the volume fraction. Excess molar volumes on mixing for the above systems have also been calculated. The density and excess molar volumes were fitted as a function of both mole fraction and temperature to a polynomial equation. The temperature dependence of derived magnitudes, ( ∂ V m E / ∂ T ) P , x and ( ∂ H m E / ∂ P ) T , x , was computed, given their importance in the study of specific molecular interactions. The experimental values of permittivity have been compared to those estimated by usual models of literature and the results indicate that the predictions are better when the volume change on mixing is incorporated in calculations. From the values of permittivity and density on mixing the dipole moment for tetraglyme was calculated. The work concludes with an interpretation of the sign of excess permittivity and its behaviour with temperature and that of excess molar volume.